1. Field of Invention
The present invention relates to a film forming apparatus that is capable of forming films sequentially with two types of film forming mechanisms in the same chamber. The present invention also relates to a base substrate to form an oxide thin film thereon, that is a substrate to form the oxide thin film on which the oxide thin film having excellent properties and electrical properties can be easily formed, and to a production method thereof.
2. Description of Related Art
A related art magnetron sputtering apparatus is described below.
The magnetron sputtering apparatus produces high density plasma on a target by applying the magnetic field that intersects with the electric field to subject a trochoid movement to electrons emitted from a cathode. Thus, this sputtering apparatus has excellent power efficiencies that can enhance a sputtering speed at a relatively low voltage.
A related art ion beam sputtering apparatus is described below.
The ion beam sputtering apparatus forms a film at a low gas pressure by taking ion beams that are accelerated at high energy from an independent ion source, and by impinging the ion beams on a target under high vacuum atmosphere.
A related art electron beam heating vacuum vapor deposition apparatus is described below.
The electron beam heating vacuum vapor deposition apparatus irradiates a material to be evaporated with electron beams, heats it and evaporates it by utilizing an electron impact. In this method, a crucible is water-cooled. Therefore, impurities within a material of the crucible have low possibility to contaminate a vapor deposition film, and a material having a high melting point, a semiconductor or an oxide can be vapor deposited.
In the above-mentioned related art sputtering apparatuses and the vapor deposition apparatus, when a first thin film is formed on the substrate by sputtering, and a second thin film is formed on the first thin film to produce an oxide thin film forming substrate, the first thin film and the second thin film cannot be formed sequentially. In other words, the substrate is introduced into a chamber of the sputtering apparatus, the first thin film is formed on the substrate by sputtering, the substrate is then taken out from the chamber, the substrate is introduced into a chamber of the vapor deposition apparatus, and the second thin film is formed on the first thin film by a vapor deposition method. Accordingly, the first thin film and the second thin film cannot be formed sequentially within the same chamber.
As an example, a Pt substrate formed in a related art batch process is described below.
A metal Pt material can change its structure depending on a forming temperature. For example, when a Pt thin film is formed on a substrate at a temperature ranging from room temperature to not exceeding 300° C., a very flat Pt substrate is formed. However, such a substrate has poor crystallinity and orientation properties as compared with the one formed by heating at 300° C. or more. Accordingly, when an oxide thin film forming solution is used to form an oxide thin film by a spin coat method and the like on the flat Pt substrate on which the Pt thin film is formed at a temperature not exceeding 300° C., poor crystallinity and orientation properties of the Pt substrate may result in poor crystallinity and orientation properties of the oxide thin film thereon, although the thin film is very easily formed.
On the other hand, when a Pt thin film is formed on the substrate at a forming temperature ranging from 300° C. to 650° C., the Pt thin film has a distinct columnar structure and its crystallinity (orientation properties) is enhanced as the temperature increases. However, a gap will be produced between Pt columns. If an oxide thin film is formed on such a Pt substrate, the oxide thin film forming solution itself or oxide thin film constituent elements will be dispersed between the Pt columns, and a composition of the oxide thin film especially at an interface with the Pt substrate will have a distribution, although the oxide thin film can easily attain excellent crystallinity and orientation.
When the Pt thin film is formed on the substrate at 650° C. or more, the film is in a granulated structure. In this case, the Pt thin film will have a surface with a poor morphology and poor orientation properties. Correspondingly, the oxide thin film thereon cannot be excellently produced.
In addition, the following is commonly applied to all of the above-mentioned Pt substrates. When the Pt thin film is formed by the sputtering method, a mechanism is used such that an inert gas or the like is changed to be a high energy plasma, the Pt target is exposed to the plasma and energy of the plasma is transferred to a Pt element of the Pt target, whereby the Pt thin film is coated on the substrate. Accordingly, the thus-formed Pt substrate contains a great amount of the inert gas. Typically, an argon (Ar) gas is often used, which results in the Pt substrate on which a great amount of Ar is adsorbed. When the oxide thin film is formed on the Pt substrate, Ar is emitted from the Pt substrate to the oxide thin film in every thermal step. This might cause peeling at the interface, perforation or poor orientation properties.